The research plan deals with the chemical asymmetry found in Bacillus subtilis DNA as it effects "strand switching" during transcription, strand bias in integration of donor DNA, repair and mutagenesis during transformation. The experimental approach involves the following: 1) Physical isolation of L-specific sporulation and H-specific germination 32P-labeled RNAs obtained by characterizing discrete-size species as displayed by electrophoresis on polyacrylamide and hybridization-competitions. 2) Utilization of these RNAs as hybridization probes to survey and recover in an EcoRI and HindIII digests, DNA fragments which specifically encode for L or H transcripts. 3) Restriction endonucleases cleavage site evaluations of the B. subtilis genome through the electrophoretic separation of prototrophic transforming fragments before and after marker "rescue" analyses involving ligation with recipient DNA that has been similarly restricted. (4) Molecular cloning in B. subtilis recE strains of transforming fragments or segments from the B. pumilus or B. licheniformis genomes using the plasmid pUB110 or pRR106 as vectors. (5) Sequence analysis of their promoter regions after their transcription pattern has been established. (6) Studies on mutational strand bias (H/L) during transformation with heteroduplex donor DNA substituted with 2-aminopurine. In vitro repair of endonuclease S1 treated mistmatched heteroduplexes with lysates from W.T. and polA deficient strains. These studies will elucidate the mechanisms which control the asymmetric transcription during morphogenesis and whether mismatch repair is an asymmetric process and error-prone during the gap-filling step by DNA polymerase I.